1. Field of the Invention
The present invention relates to a chip coil and a printed circuit board for the same, which are used for, for example, compact communication equipment, electronic devices or the like.
2. Description of the Related Art
As sizes and weights of electronic devices are reduced, requests for reduction in size (integration onto a chip) of electronic components increase. Coils which are used for various communication equipment are not exceptions, and coils and inductors, which are chip electronic components to be used by mounting on those communication equipment, have been developed.
As disclosed in Japanese Patent Application Laid-Open No. 9-219318, for example, a chip inductor, which is a chip electronic component, forms a coil made by winding a conductive wire around a square pole winding drum, which has flange-shaped brims protruding from both edges. And, formed on part of the end faces of those brims are plated electrodes.
FIG. 20 shows an example of a configuration of a conventional chip inductor. This chip inductor 960 has electrodes 965 and 967, which are formed on the entire surface of the brims of a core, and is mounted upon a printed circuit board (not shown in the drawing) so that the direction of the length thereof can be the same as the running direction of patterns 961 and 963, which are signal lines on that printed circuit board. In other words, as shown in FIG. 21, the conventional chip inductor has signal lines 961 and 963 and land patterns at positions of preventing magnetic fluxes 971 and 973 of a coil when mounted on the printed circuit board.
In addition, the results from carrying out an electromagnetic field simulation considering magnetic flux concentration distribution of the core in the above-described conventional chip inductor show that, as shown in FIG. 22, concentration of magnetic fluxes has occurred at the portions indicated by symbols (O) in the brims 962 and 964, which are components of the core. In other words, as is seen from FIGS. 20 and 22, the conventional chip inductor has a configuration where electrodes 965 and 967 are formed at the magnetic flux concentrated portions of the core.
There are problems with the conventional inductor in which the above-described configuration causes increase in magnetic loss and decrease in the Q value of inductor.
There is another problem with the conventional inductor in which the wiring pattern for mounting the inductor on the printed circuit board may prevent the magnetic fluxes from normally running due to the positions of the electrodes.
The present invention has been developed in view of the above-described problems, and aims to provide a chip coil and a printed circuit board for the same, which reduce magnetic loss and prevent decrease in sensitivity characteristics and the Q value and are suitable for use as an antenna for wireless communications by mounting on various wireless communication equipment (e.g., radio frequency identification (RFID)).
In addition, another objective of the present invention is to provide a chip coil and a printed circuit board for the same, which allow an arrangement of wiring patterns that reduce magnetic loss and prevent decrease in the Q value when mounted on the printed circuit board.